while True:
    print("\n1: 登陆\n2: 注册\n3: 联系客服")
    choice = input("请选择(1-3): ")

    if choice == '1':
        print("您选择了: 登陆")
        break
    elif choice == '2':
        print("您选择了: 注册")
        break
    elif choice == '3':
        print("您选择了: 联系客服")
        break
    else:
        print("输入错误，请重新输入")